We study a class of cyclic Brownian heat engines in the framework of finite-time thermodynamics. For infinitely long cycle times, the engine works at the Carnot efficiency limit producing, however, zero power. For the efficiency at maximum power, we find a universal expression, different from the endoreversible Curzon-Ahlborn efficiency. Our results are illustrated with a simple one-dimensional engine working in and with a time-dependent harmonic potential.

Efficiency at maximum power: An analytically solvable model for stochastic heat engines

A digital twin is a virtual representation of a physical object or process capable of collecting information from the real environment to represent, validate and simulate the physical twin’s present and future behavior. It is a key enabler of data-driven decision making, complex systems monitoring, product validation and simulation and object lifecycle management. As an emergent technology, its widespread implementation is increasing in several domains such as industrial, automotive, medicine, smart cities, etc. The objective of this systematic literature review is to present a comprehensive view on the DT technology and its implementation challenges and limits in the most relevant domains and applications in engineering and beyond.

https://www.mdpi.com/2072-4292/14/6/1335/pdf?version=1646876144

Digital Twin Technology Challenges and Applications: A Comprehensive Review

A newly introduced term in the field of simulating an artificial or physical system is that of the “Digital Twin” concept method. It employs a digital representation and modeling method, capable of expanding and improving the life cycle of complex items, systems, and processes. Nowadays, digital twin technology has become a key research field worldwide. In this context, it is applied and utilized in various fields. One such field is the automotive industry, a technological field that has great implications in users’ everyday life. Digital twin technology not only has great contributions from the initial stages of design until the final construction stages of vehicles, but also during its use, drawing useful information from its daily functions and making the driving experience more enjoyable, comfortable, and safe. It is worth noting that the vehicles that can greatly benefit from the use of digital twins are electric vehicles, which has tended to acquire greater shares in the last decade.

/pdf/digital-twins-in-the-automotive-industry-the-road-toward-22vrd3a7.pdf

Digital Twins in the Automotive Industry: The Road toward Physical-Digital Convergence

Abstract A finite source heat engine’s optimal configuration is studied. The model includes thermal resistance, heat leakage, a complex heat transfer law, and a heat source with variable temperature. The optimization objective is that the output work is the largest. The influences of factors such as the heat transfer law and heat leakage are analyzed. The results of this paper are universal and inclusive, and provide certain theoretical support for the performance improvement of actual heat engines.

Optimal Configuration of Finite Source Heat Engine Cycle for Maximum Output Work with Complex Heat Transfer Law

https://iopscience.iop.org/article/10.1088/1742-5468/2016/07/073202/pdf

Irreversible and endoreversible behaviors of the LD-model for heat devices: the role of the time constraints and symmetries on the performance at maximum χ figure of merit

A Muser-type engine model can be taken as a particular case of a Curzon–Ahlborn thermal cycle, when the upper thermal conductance is finite and the lower one is infinite. In addition, the upper heat exchange is given by the Stefan–Boltzmann law. That model is suitable to thermodynamically describe some aspects of energy converters as solar cells and photosynthetic systems. In the present article, we call n -Muser engine to an engine of the Muser type in which the T 4 heat transfer law is substituted by a T n -law, being n > 0 a real number. Here, we show that if we use the so-called ecological criterion of merit to optimize finite-time heat engines to compare the thermodynamic performance of the n -Muser engines under approximate terrestrial conditions (see below), we obtain that n = 4 accomplishes the best performance. This same result was obtained by using data from the rest of planets of the solar system.

The role of the Stefan-Boltzmann law in the thermodynamic optimization of an n-Müser engine

This paper presents an optimal performance analysis for an isothermal model which performs work at a steady state via the energy transfer from a chemical reaction, using the methodology of the so-called Finite Time Thermodynamics (FTT). Furthermore, three optimal operation modes namely, Maximum Power, Maximum Omega function and Efficient Power are presented for the model. Results show analogies in the optimal performance between thermal and isothermal engine models.

Optimum performance for energy transfer in a chemical reaction system

In a recent paper (Ramirez-Moreno, Gonzalez-Hernandez and Angulo-Brown, 2016) it was discussed the thermodynamic performance of a family of n -Muser engines under the so-called ecological optimization criterion for finite-time heat engines. In this reference it was shown that a 4 -Muser engine accomplishes the best performance in comparison with any other n -Muser engine with n ≠ 4 . However, this result was obtained for Muser engines operating under the condition of C = C m a x ; that is, maximum solar concentration factor. In the present paper we show that the result previously described is also valid for arbitrary values of the concentration factor C .

Ecological optimization of a family of n-Müser engines for an arbitrary value of the solar concentration factor

In this paper, a semiclassical approach is used to describe a kind of black-body which we will call a matte black-body. Although the frequency energy density of a black-body is deduced using a semiclassical method which includes the electromagnetic reaction force and the quantization of the energy, a phenomenological damping force, as in the explanation of the anomalous dispersion of some fluids, is considered in order to obtain the corresponding frequency energy density of the matte black-body. The concept of emissivity is incorporated into the new body in order to explain the experimental data of the radiation measured in the Earth's atmosphere. The purpose of this article consists of showing students the applicability of semiclassical approaches in obtaining physical results.

M.A. Ramírez-Moreno

Papers

Digital Twin Technology Challenges and Applications: A Comprehensive Review

The role of the Stefan-Boltzmann law in the thermodynamic optimization of an n-Müser engine

Optimum performance for energy transfer in a chemical reaction system

Ecological optimization of a family of n-Müser engines for an arbitrary value of the solar concentration factor

A semiclassical approach to the matte black-body